Designing the Voltage Feedback Circuit

Summary. Be very careful in selecting a control IC for your application  

The only function of the voltage feedback loop is to hold the output voltage(s) at a constant value. Complications arise in areas such as transient load response, accuracy of the output(s), multiple outputs, and isolated outputs. All of these individually can be nightmares for the designer, but if the design approaches are understood then each factor can easily be satisfactorily addressed. 

To begin the proeess, one deeides how mueh sense eurrent is to be drawn through the output voltage resistor divider. For the sake of reasonable values to be ealeulated for the error amplifier eompensation values, resistanee values in the range of 1.5 to 15 K should be used in the upper leg of the resistor divider. Tet us use a sense eurrent of 1 mA as the resistor divider sense eurrent. This makes the lower resistor in the divider (Ri) 

Continuing the design example, let us use the elosest f pereent resistor value -2.49 K. This makes the aetual sense eurrent 

That eompletes its set-up. Tater, the eompensation around the amplifier needs to be done to set the de gain and the bandwidth performanee. 

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